Folding device

Abstract

The invention relates to a clinching press comprising a press tool (52) and a prebending unit (1) to produce a reciprocating movement in a tool holder (14) of a prebending tool (12), said tool holder being articulated to a foundation (2). The prebending unit (1) has a pressure rod (50) coupled to the press tool (52) and a knee-joint mechanism (28, 30), joined, on the one hand, to a pivot point (36) on the tool holder (14) and, on the other hand, to a fixed pivot point (34) on the foundation (2). The pressure roller (46) is freely rotatably mounted at the connecting point (32) of the links (28, 30). The knee-joint mechanism (28, 30) has a gas pressure spring (38, 42) for returning the mechanism to the starting position shown. The knee-joint mechanism (28, 30) can be moved under the influence of the pressure rod (50), in a continuous movement from the bent-out in the position shown to a position bent-out in the opposite direction, the tool holder (14) being displaceable along a predetermined path of movement between a starting position, a work position and an end position.

We claim: 
     
       1. Clinching press comprising a press tool (52) and a pre-bending unit (1) for producing a reciprocal movement of a tool holder (14) pivotally joined to a foundation (2), said tool holder being supported in such a manner that it is displaceable, through motion of an operating means (50) coupled to the press tool (52), along a predetermined path of movement between a starting position, a work position and an end position, and the tool holder (14) being provided with a return means (38, 42) for returning the tool holder (14) to its starting position, and a knee-joint mechanism (28, 30), which, in the form of two articulated lengths, is joined, at one end, to a pivot point (36) on the tool holder (14), and, on the other hand, to a stationary pivot point (34) in the foundation, wherein the knee-joint mechanism (28, 30), under influence of the operating means (50), can be moved in a continuous movement from a first bent-out position where the tool holder (14) is in its starting position, via a completely extended position where the tool holder (14) is in its work position, to a second bent-out position where the tool holder (14) is in its end position, and the returning means (38, 42) being arranged to return the knee-joint mechanism (28, 30) and the tool holder (14) in a reversed continuous movement from the second bent-out position, via the completely extended position to the first bent-out position, where the tool holder (14) once again takes its starting position. 
     
     
       2. Device according to claim 1, wherein, when the knee-joint mechanism (28, 30) is in one of its bent-out positions, a prebending tool (12) mounted in the tool holder (14) will be off-set a predetermined distance from a path of a final bending tool (60) arranged in the press tool (52). 
     
     
       3. Device according to claim 1, wherein the operating means is in the form of a pressure rod (50), a free end of which (48) can be pressed against a freely rotatable roller (46) which is journalled at the point of connection (32) between the articulated lengths (28, 30). 
     
     
       4. Device according to claim 3, wherein the free end (48) of the pressure rod (50) is flat and the pressure rod is of adjustable length. 
     
     
       5. Device according to claim 1, wherein the tool holder (14) is supported by two links (16, 18), which are journalled in pivot points (20, 24) in the foundation (2), and in pivot points (22, 26) in the tool holder (14). 
     
     
       6. Device according to claim 5, wherein the links (16, 18) are of equal length. 
     
     
       7. Device according to claim 1, wherein the return means (38, 42) consists of a gas spring, connected to a pivot point (40) positioned off-set of an assumed line through pivot points (34, 36) at ends of the knee-joint mechanism (28, 30) in the completely extended position. 
     
     
       8. Device according to claim 3, wherein the free end (48) of the pressure rod (50) supports a flat pressure plate. 
     
     
       9. Clinching press comprising a foundation (2);   a press tool (52);   a tool displacement means (50) coupled to the press tool (52); and   at least one pre-bending unit (1), the pre-bending unit comprising: a tool holder (14) which is reciprocally attached to the foundation (2) to allow movement along a predetermined path;   a knee-joint mechanism (28, 30) connecting the tool holder (14) to the foundation (2); and   a return means (38, 42) which urges the knee-joint mechanism (28, 30) into a first bent position with the tool holder (14) in a starting position; wherein     displacement of the press tool (52) toward a work piece (8) moves the tool displacement means (50) into contact with the knee-joint mechanism (28, 30) in the first bent position while the tool holder (14) is in the starting position;   further displacement of the tool displacement means (50) moves the knee-joint mechanism (28, 30) into a fully extended position, moving the tool holder (14) to an end of the predetermined path into a work position;   still further displacement of the tool displacement means (50) moves the knee-joint mechanism (28, 30) beyond the fully extended position into a second bent position on a side of the fully extended position opposite that of the first bent position, thereby moving the tool holder (14) back along the predetermined path away from the end position; and   retraction of the tool displacement means (50) allows the return means (38, 42) to move the knee-joint mechanism (28, 30) back through the fully extended position to the first bent position, which correspondingly moves the tool holder (14) through the work position to the starting position.   
     
     
       10. The clinching press of claim 9, further comprising two links (16, 18) connecting the tool holder (14) to the foundation (2), each of the links having a first end pivotally attached to the foundation (2) and a second end pivotally attached to the tool holder (14). 
     
     
       11. The clinching press of claim 10, wherein the links (16, 18) are of equal length. 
     
     
       12. The clinching press of claim 9, wherein the return means (38, 42) is pivotally attached at a first end to the foundation (2) and at a second end to the knee-joint mechanism (28, 30). 
     
     
       13. The clinching press of claim 12, wherein the return means comprises a gas spring. 
     
     
       14. The clinching press of claim 9, wherein the displacement means (50) comprises a pressure rod, a free end of which contacts a roller (46) disposed at a knee joint (32) of the knee-joint mechanism (28, 30). 
     
     
       15. The clinching press of claim 14, wherein the pressure rod is of adjustable length. 
     
     
       16. The clinching press of claim 9, wherein the knee-joint mechanism (28, 30), when positioned at either the first bent position or the second bent position, places a prebending tool (12) mounted in the tool holder (14) at least a predetermined minimum clearance distance from a final bending tool (60 62) disposed on the press tool (52). 
     
     
       17. The clinching press of claim 9, wherein two prebending units are disposed on the foundation (2) on opposite sides of the press tool (52). 
     
     
       18. Clinching press comprising a foundation (2);   a press tool (52);   a pressure rod (50) coupled to the press tool (52); and   at least one pre-bending unit (1), the pre-bending unit comprising: a tool holder (14) which is reciprocally attached to the foundation (2) by two pivotally attached links of equal length to allow movement of the tool holder (14) along a predetermined, arcuate path;   a knee-joint mechanism (28, 30) connecting the tool holder (14) to the foundation (2); and   a return means (38, 42) comprising a gas spring pivotally attached at a first end to the foundation (2) and at a second end to the knee-joint mechanism (28, 30), the return means urging the knee-joint mechanism (28, 30) into a first bent position with the tool holder (14) in a starting position; wherein     displacement of the press tool (52) toward a work piece (8) moves the pressure rod (50) into contact with the knee-joint mechanism (28, 30) in the first bent position while the tool holder (14) is in the starting position;   further displacement of the pressure rod (50) moves the knee-joint mechanism (28, 30) into a fully extended position, moving the tool holder (14) to an end of the predetermined path into a work position;   still further displacement of the pressure rod (50) moves the knee-joint mechanism (28, 30) beyond the fully extended position into a second bent position on a side of the fully extended position opposite that of the first bent position, thereby moving the tool holder (14) back along the predetermined path away from the end position; and   retraction of the pressure rod (50) allows the return means (38, 42) to move the knee-joint mechanism (28, 30) back through the fully extended position to the first bent position, which correspondingly moves the tool holder (14) through the work position to the starting position.